[Facts that explain the host specificity of helminths].

Extracts from larvae of Trichinella spiralis, mature Ascaridia galli and Ascaris suum and blood sera of their possible hosts (rats, pigs, chicks, guinea pigs, mice and men) were investigated by the method of electrophoresis in polyacrylamide gel. The protein component was found to be most identical in helminth and its obligate host. The host specificity is supposed to depend on the community of the protein content of the parasite and its host. The data on the difference in protein spectra are given and the peculiarities of the evolution of mono- and polyhost helminths are discussed.